Introduction to power microelectronic devices

At the dawn of the energy transition, accelerated by the scarcity of fossil fuel resources and the growing awareness of environmental and ecological issues, delivering electrical energy to customers over long distances from multiple renewable (or non-renewable) sources poses challenges in power conversion, where active power components play an essential role.

HVDC (direct current, very high voltage) transmission requires converters with working voltages approaching 10 kV, and forces us to rethink their architectures. These converters are based on power switches made from semiconductor materials. Their study is a matter for power microelectronics. With the same roots as signal microelectronics, power microelectronics has evolved with the development of its own technologies. For example, there are no IGBTs for signal electronics, and superjunctions are of only limited interest.

While signal microelectronics focused on miniaturizing components by reducing the engraving "finesse" of components, power microelectronics, which focuses on delivering electrical energy to consumers' homes, has always sought components that can withstand much higher voltages (up to several thousand volts). The aim has always been to achieve the best compromise between the voltage to be supported and the admissible current density (up to 100 A.cm ^-2 ), by trying to favour vertical components that could take advantage of the entire volume of the semiconductor substrate on which they rest.

Produced in this way from semiconductor materials, these components will always be dependent on their physical properties, which explains the performance limitations, such as avalanche voltages limited by insufficient critical electric fields, or on-state resistances that are always too high because of the trade-off between on-state and off-state.

This article presents the main workings of bipolar diodes, current-controlled bipolar transistors and voltage-controlled MOSFET and IGBT transistors. Avalanche and conduction phenomena are discussed in relation to the topology of the structure and the mechanisms to be implemented. The article concludes with a summary of the development of wide-bandgap materials, commonly known as large-gap semiconductor materials. With physical properties far superior to those of silicon, large-gap devices are already on the market, notably those made of silicon carbide (SiC) and gallium nitride (GaN). The development of these technologies and their challenges are reviewed.

A glossary of terms is provided at the end of the article.